Apparatus, system, and method for detecting temperature threshold events in an aftertreatment device

ABSTRACT

An apparatus, system, and method are disclosed for detecting temperature threshold events in an aftertreatment device. The system may include an aftertreatment device configured to treat an exhaust gas of an internal combustion engine and a temperature responder disposed within a region of interest of the aftertreatment device. The temperature responder is configured to melt at a threshold temperature. The system may further include two access points electrically coupled to the temperature responder and an observation module configured to measure an electrical resistance value across the two access points. The observation module detects the melting of the temperature responder based on the electrical resistance value measured across the access points. In alternate embodiments the observation module is included within an engine control module (ECM) or a service tool.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to aftertreatment devices for treating engineexhaust streams, and more particularly relates to detecting theoccurrence of temperature threshold events in aftertreatment devices.

2. Description of the Related Art

Emissions regulations for internal combustion engines have changedrapidly in recent years. To meet the new regulations, many enginemanufacturers have had to install aftertreatment devices to reduceemissions in the exhaust gases, or to condition the exhaust gases toassist other aftertreatment devices. For example, particulate filtersremove soot from the exhaust gases of a diesel engine, and dieseloxidation catalysts are sometimes used to generate temperature in theexhaust gas to assist a particulate filter in oxidizing the soot off ofthe filter.

Most aftertreatment devices experience thermal cycles during theoperations of the engine. The thermal cycles may be intentional, forexample during the removal of soot from a particulate filter, orunintentional such as when the engine experiences large changes in therequired workload for the engine. Each thermal cycle induces atemperature gradient within the device. The temperature gradient withinthe device may cause stresses and over time can cause the aftertreatmentdevice to fail. In general, the higher the maximum temperatureexperienced within the aftertreatment device, the larger the thermalgradient within the aftertreatment device. A high temperature can alsocause stress and/or failure of an aftertreatment device independent ofthe temperature gradient induced in the device.

A stress related failure within an aftertreatment device, such as acrack in the wall of the aftertreatment device, can be particularlydifficult to detect. There are no direct measurements routinely used inreal-time for applications to detect such failures. Even when anaftertreatment device is being serviced, it is difficult for a servicetechnician to detect such a failure even if the technician has a reasonto look for it.

The aftertreatment device typically comprises a core—such as cordieriteor silicon carbide honeycomb structure—wrapped in an insulating materialthat fixes the core in place, and the whole device is typically coveredby a sheet metal and/or stainless steel shell or “can.” A stress failureon a device occurs in the core, typically as radial cracking around thesurface of the core, and is not visible to a technician merely handlingthe device. Therefore, the current detection failure schemes rely oneither ultrasound or special visual inspection to determine whether anaftertreatment component has failed.

Ultrasound detection schemes are problematic because of the intentionalporous nature of the aftertreatment devices, and the gaps in thesurrounding insulating material. The ultrasound frequency must be so low(causing a low resolution image), and the aftertreatment devices are sopoorly configured for ultrasound analysis, that often only the mostcatastrophic failures can be detected. However, some aftertreatmentdevices are no longer design compliant—which can mean regulatoryemissions thresholds are not being met—with only a few moderate cracksaround the device.

Special visual inspections require optic tools allowing the technicianto view the interior of channels within the aftertreatment device. Thechannels of the device may be packed with soot and/or debris, renderingthe inspection difficult or impossible. A minimal check of the devicemay require checking hundreds of channels around the perimeter of anaftertreatment device by repeatedly inserting a tool designed to go intosmall diameter channels which are at a packing density of 200-300 cellsper square inch. The inspection procedure can damage the aftertreatmentdevice, and is time consuming and costly under the best ofcircumstances.

Even where physical device failure of the aftertreatment device can bedetected, high temperatures within the aftertreatment device can causeexcessive degradation short of physical device failure. For example, anaftertreatment device may be expected to crack at 950 degrees C., butexperience severe catalyst deactivation at 850 degrees C. with nophysical indications of degradation. Catalyst degradation may induceadditional stress on the device—for example increasing the averagetemperature at which soot oxidation can occur, and catalyst degradationmay cause emissions increases. An aftertreatment device may beexperiencing increased emissions without being detected.

A detection of the true temperature within the aftertreatment device iscurrently beyond the current technology at commercially reasonableprices. Current aftertreatment systems place a temperature sensingdevice—usually a thermistor and/or a thermocouple—just upstream and/ordownstream of the aftertreatment device. The temperature within theaftertreatment device is often estimated as a function of thesetemperatures—for example a weighted average of the temperatures, or athermal model based on the temperatures and estimated hydrocarbon orsoot burning rates within the aftertreatment device plus estimated heattransfer effects. While the current temperature estimates are acceptablefor certain estimates such as determining soot oxidation rates in steadystate operation, the current temperature estimates do not estimate peaktemperature events in transients very well. For example, a temperaturespike may occur within the aftertreatment device, but the delay on thetemperature sensing devices may cause the temperature sensing device tomiss the highest portions of the spike and show temperatures 100 deg C.or more lower than the actual temperature event experienced within theaftertreatment device.

These limitations in the current technology introduce the risksattendant with aftertreatment devices with hidden defects. For example,a service company may clean aftertreatment devices and swap them out fora dirty aftertreatment device in a customer vehicle. Under the currentstate of technology, there is a significant risk that one of the swappedaftertreatment devices may have a stress failure or degraded catalyst,penalizing either the customer or the service company according to whichdevice has failed.

SUMMARY OF THE INVENTION

From the foregoing discussion, applicant asserts that a need exists foran apparatus, system, and method that provides for detecting temperaturethreshold events in an aftertreatment system.

The present invention has been developed in response to the presentstate of the art, and in particular, in response to the problems andneeds in the art that have not yet been fully solved by currentlyavailable aftertreatment temperature detection systems. Accordingly, thepresent invention has been developed to provide an apparatus, system,and method for detecting temperature threshold events that overcome manyor all of the above-discussed shortcomings in the art.

An apparatus is disclosed for detecting temperature threshold events inan aftertreatment device. The apparatus comprises a temperatureresponder disposed within a region of interest of an aftertreatmentdevice. The temperature responder comprises a structure formed of amaterial configured to melt at a threshold temperature. The apparatusfurther comprises an observation module configured to detect the meltingof the temperature responder.

The apparatus may further comprise two access points. The temperatureresponder is configured to electrically couple the two access points,and the observation module is configured to measure an electricalresistance value across the two access points. The observation moduledetects the melting of the temperature responder based on the electricalresistance value. The apparatus comprises a thermal event moduleconfigured to determine whether a region of interest of theaftertreatment device has exceeded the threshold temperature based onthe melting of the temperature responder.

The apparatus may further comprise a plurality of temperatureresponders, each temperature responder comprising a structure formed ofa material configured to melt at a distinct threshold temperature. Theplurality of temperature responders are configured to electricallycouple the two access points in parallel. The thermal event module isfurther configured to determine whether the region of interest of theaftertreatment device has exceeded each distinct threshold temperaturebased the melting of each temperature responder. The apparatus furthercomprises the temperature responder disposed within an encapsulationdevice comprising a gas impermeable chamber.

The apparatus may further comprise an electronic control module (ECM).The ECM may comprise an observation module, a thermal event module, anda fault module. The thermal event module may set a thermal eventindicator based on the melting of a temperature responder and the faultmodule may set a fault indicator based on the thermal event indicator.

A method is disclosed for detecting temperature threshold events in anaftertreatment device. The method comprises inserting a temperatureresponder into a region of interest in an aftertreatment device andchecking the temperature responder for melting after a period ofoperation of the aftertreatment device. The method further comprisesdetermining whether the region of interest of the aftertreatment devicehas exceeded the threshold temperature based on the melting of thetemperature responder.

A system is disclosed for detecting temperature threshold events in anaftertreatment device. The system comprises an aftertreatment deviceconfigured to treat an exhaust gas of an internal combustion engine. Thesystem further comprises the apparatus to detect temperature thresholdevents in the aftertreatment device. The system may further comprise anelectronic control module (ECM) comprising the observation module, athermal event module configured to set a thermal event indicator basedon a temperature responder melting in a region of interest, and a faultmodule configured to set a fault indicator base on the thermal eventindicator.

The system may further comprise a service tool. The service tool maycomprise the observation module, a thermal event module configured toset a degradation indicator based on the region of interest of theaftertreatment device exceeding the threshold temperature, and a displaymodule configured to provide the degradation indicator to a displayoutlet.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussion of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize that theinvention may be practiced without one or more of the specific featuresor advantages of a particular embodiment. In other instances, additionalfeatures and advantages may be recognized in certain embodiments thatmay not be present in all embodiments of the invention.

These features and advantages of the present invention will become morefully apparent from the following description and appended claims, ormay be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readilyunderstood, a more particular description of the invention brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are nottherefore to be considered to be limiting of its scope, the inventionwill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is an illustration depicting one embodiment of a system fordetecting temperature threshold events in an aftertreatment device inaccordance with the present invention;

FIG. 2 is a schematic block diagram illustrating one embodiment of acontroller to determine whether the region of interest of anaftertreatment device has exceeded the threshold temperature inaccordance with the present invention;

FIG. 3 is an illustration depicting one embodiment of an apparatus fordetecting thermal events in an aftertreatment device in accordance withthe present invention;

FIG. 4 is an illustration depicting one embodiment of an apparatus fordetecting thermal events in an aftertreatment device in accordance withthe present invention; and

FIG. 5 is a schematic flow chart diagram illustrating one embodiment ofa method for detecting temperature threshold events in an aftertreatmentdevice in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the figures herein,may be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the apparatus, system, and method of the presentinvention, as presented in FIGS. 1 through 5, is not intended to limitthe scope of the invention, as claimed, but is merely representative ofselected embodiments of the invention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of materials, fasteners, sizes, lengths, widths, shapes, etc.,to provide a thorough understanding of embodiments of the invention. Oneskilled in the relevant art will recognize, however, that the inventioncan be practiced without one or more of the specific details, or withother methods, components, materials, etc. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the invention.

FIG. 1 is an illustration depicting one embodiment of a system 100 fordetecting temperature threshold events in an aftertreatment device 106in accordance with the present invention. The system 100 may comprise aninternal combustion engine 102 that produces exhaust gas 104 as abyproduct of operation. For example, the engine 102 may be a dieselengine 102. The system 100 further comprises an aftertreatment device106 configured to treat the exhaust gas 104. In one embodiment theaftertreatment device 106 may comprise a particulate filter configuredto remove particulates from the exhaust gas 104. In alternativeembodiments, the aftertreatment device 106 may be a diesel oxidationcatalyst, a NO_(X)-adsorption catalyst, and/or other aftertreatmentdevices 106 known in the art.

The system 100 further comprises a temperature responder 108 disposedwithin a region of interest of the aftertreatment device 106. In oneembodiment, the system 100 may comprise a plurality of temperatureresponders 108 disposed within each of a plurality of areas of interestwithin the aftertreatment device 106. The temperature responder 108comprises a structure formed of a material configured to melt at athreshold temperature. The thermal responder 108 may be one of a wireand a material deposited on a surface of a channel within theaftertreatment device 106. The temperature responder 108 may comprise anelectrically conductive material that may be sprayed, painted, plated,etched, printed, and/or inserted into a channel, or a plurality ofchannels, of the aftertreatment device 106 during manufacture. In analternate embodiment, the temperature responder 108 may be placed withinan aftertreatment device 106 by a service technician, for example to runa test and determine if a threshold temperature is reached in theaftertreatment device 106 during a test operating period.

The threshold temperature may be a temperature at or near a selectedtemperature of interest. For example, a selected temperature of interestmay be about 400 degrees C. where a NO_(x) based regeneration of sootmay be expected to occur in a soot filter 106 in one embodiment of thesystem 100. In the example, the selected material for the temperatureresponder 108 material may be zinc (Zn), which melts at about 420degrees C. The melting of the zinc would indicate that the thresholdtemperature for the particulate regeneration event has occurredsuccessfully.

In another example, the threshold temperature of interest may becorrelated to a desired desulfation event within a catalyticaftertreatment device 106, which may require a temperature of about 750degrees C. for one embodiment of the system 100. In the example, thematerial selected for the temperature responder 108 material may becalcium, which melts at around 840 degrees C., or a platinum-titaniumeutectic alloy, which melts at around 840 degrees C. In otherembodiments of the system 100, temperatures known to degrade a catalyst,known to degrade the physical structure of an aftertreatment device,and/or known to destroy the aftertreatment device 106 may be selectedtemperatures of interest. For example, an aftertreatment device 106 maybe known to suffer catastrophic damage above temperatures in the 1000deg C. temperature range, and silver, gold, and/or copper may melt inthe range of the selected temperature of interest. In one embodiment,the temperature responder 108 may comprise magnesium or aluminum. Basedon the disclosures herein, it is a mechanical step for one of skill inthe art to choose a threshold temperature and a material that melts inan appropriate range for the threshold temperature.

The system 100 may further comprise a plurality of temperatureresponders 108, each comprising a structure formed of a material to meltat a distance threshold temperature. In one embodiment, the temperatureresponders 108 may be configured to melt at a wide range of temperaturesto check for different temperature threshold events. For example, thetemperature responders 108 may comprise zinc, calcium, and silvermelting at about 420 deg C., 840 deg C., and 960 deg C. In oneembodiment, the temperature responders may be configured to melt in anarrow range of temperatures to bracket a temperature threshold event.For example, the temperature responders 108 may comprise brass, silver,and copper melting at just above 900 deg C., 960 deg C., and 1080 deg C.that may provide additional resolution to narrow down the achievedtemperature during a temperature threshold event. The thresholdtemperatures, temperatures of various regeneration events, andtemperatures causing damage to various aftertreatment devices 106 varysignificantly for each system 100. The included examples areillustrative only and do not limit the scope of the present invention.

The system 100 may further comprise two access points 110, wherein thetemperature responder 108 is configured to electrically couple the twoaccess points 110. For example, the access points 110 may beelectrically connected by a wire 108. In one embodiment, each of the twoaccess points 110 exits the aftertreatment device 106 from opposite endsof the aftertreatment device 106 as shown in FIG. 1. In an alternateembodiment, the two access points 110 exit from the same end of theaftertreatment device 106 (for example, refer to FIG. 3). The accesspoints 110 may provide access for a technician to attach an ohmmeter114B, they may be capped to prevent corrosion, they may be hardwiredinto an onboard ECM 116, and the like. In one embodiment, the accesspoints 110 are hardwired into an onboard ECM 116 by wiring the accesspoints 110 to a separate computer (not shown) that reads the electricalresistance value across the access points 110 and publishes theelectrical resistance value to a datalink (not shown) in communicationwith the ECM 116. The access points 110 may comprise the electricallyconductive terminals of a connector (not shown) such that an ohmmeter114B and/or other tool can be conveniently connected to the accesspoints 110.

The system 100 further comprises an observation module 114 configured tomeasure an electrical resistance value 112 across the two access points110, and detect the melting of the temperature responder 108 based onthe electrical resistance value 112. In one embodiment the observationmodule 114 may be a person 114A that physically removes the temperatureresponder(s) 108 from the aftertreatment device 106 and visuallyinspects the temperature responder(s) 108 for melting. Based on whetherthe visual inspection reveals melting of the temperature responder 108the person 114A may make a determination about the serviceability of theaftertreatment device 106 and/or record the information in a writtenservice log and/or on an electronic device.

In an alternate embodiment, the observation module 114 may be anohmmeter 114B, or similar electrical resistance detection device,electrically attached across the access points 110 to read theelectrical resistance value 112. The electrical resistance value 112 maybe communicated to a laptop computer 120 and/or other device forinterpretation and storage. The laptop computer 120 and ohmmeter 114Bmay comprise a service tool 122 that detects temperature thresholdevents in the aftertreatment device 106. The functions of the servicetool 122 may be combined into different hardware than shown in FIG. 1,for example as an integrated tool 122. The service tool 122 maydetermine the electrical resistance value 112 by reading a stored memoryvalue from an engine control module (ECM) 116. In one embodiment, aperson (not shown) may read the electrical resistance value 112 from theohmmeter 114B.

In one embodiment of the system 100, the observation module 114 may beincluded within an ECM 116 to measure the electrical resistance value112 across the two access points 110. Measuring the electricalresistance values 112 may comprise a direct measurement, reading a valuefrom a network and/or datalink, and the like. The ECM 116 may comprise asingle device or a series of devices distributed throughout the system100. The ECM 116 may be further configured to determine whether theaftertreatment device 106 has exceeded a threshold temperature based onthe melting of the temperature responder 108. For example, the ECM 116may determine whether the electrical resistance value 112 is consistentwith an open circuit between the access points 110 corresponding to themelting of the temperature responder 108.

The ECM 116 may be further configured to set a fault indicator 118 basedon determining that a temperature responder 108 has melted exceeding athreshold temperature. The fault indicator 118 may be a lit dashboardlamp 118, a network data value (not shown), and/or a communicated signal(not shown). The fault indicator 118 may signify that an aftertreatmentdevice 106 requires service, and/or signify that an aftertreatmentdevice 106 requires replacement. In one embodiment, the ECM 116 may setan internal fault code that will alert a service technician 114A to theoccurrence of the temperature threshold event when the servicetechnician 114A engages a service tool 122 with the ECM 116.

FIG. 2 is a schematic block diagram illustrating one embodiment of acontroller 200 to determine whether the region of interest of anaftertreatment device 106 has exceeded the threshold temperature inaccordance with the present invention. The controller may be an ECM 116installed on a vehicle, and/or a service tool 122.

The controller 200 comprises an observation module 114 that measures anelectrical resistance value 112 across the access points 110 and detectsthe melting of the temperature responder(s) based on the electricalresistance value 112. The observation module 114 may set a temperatureresponder(s) 108 melted signal 202 when the temperature responder(s) 108are melted. For example, the observation module 114 may detect themelting of the temperature responder(s) 108 by determining whether theelectrical resistance value 112 is a value consistent with an opencircuit between the access points 110.

The controller 200 may comprise a thermal event module 204 configured todetermine whether the region of interest of the aftertreatment device106 has exceeded the threshold temperature based on the melting of thetemperature responder(s) 202. For example, the thermal event module 204may read the temperature responder(s) 108 melted signal 202 anddetermine the region of interest of the aftertreatment device 106 hasexceeded the threshold temperature if the thermal responder 108 hasmelted. In one embodiment, the thermal responder(s) 108 may compriseseveral thermal responder(s) 108 configured to melt at distincttemperatures, and the thermal event module 204 may determine that thethreshold temperatures of the thermal responder(s) 108 that are meltedhave been exceeded, and that the threshold temperatures of the thermalresponder(s) 108 that have not melted have not been exceeded.

The thermal event module may set a thermal event indicator 206 based onthe region of interest of the aftertreatment device 106 exceeding thethreshold temperature. The thermal event indicator 206 may be a valuestored on the ECM 116 or other device to record the thermal history ofan aftertreatment device 106. For example, the thermal event module 204may store a time value indicating when an aftertreatment device 106exceeded a certain temperature threshold.

The controller 200 may further comprise a fault module 208 configured toset a fault indicator 118 based on the thermal event indicator 206. Forexample, the thermal event indicator 206 may indicate that theaftertreatment device 106 has experienced a catastrophic temperaturethermal event, and the fault module 208 may set a fault indicator 118consistent with a failed aftertreatment device 106. The fault indicator118 may be a lit dashboard lamp, a network data value, a communicatedsignal, and/or other fault indications known in the art.

In one embodiment, the fault indicator 118 may comprise the lighting ofa malfunction indicator lamp (MIL) when catastrophic failure of theaftertreatment device 106 is indicated, and a fault code 118 publishedto a data network when a high temperature event that may not becatastrophic is indicated 206. In one embodiment, the temperaturethreshold may comprise a temperature consistent with a desulfation ofthe aftertreatment device 106, and the fault module 208 may set a faultindicator 118 consistent with a sulfur-poisoned catalyst when anapplication usage threshold is exceeded and a thermal event sufficientto drive sulfur off a catalyst in the aftertreatment device 106 has notoccurred. In one example, the application usage threshold may be vehiclemiles, a time of engine 102 operation, a total fuel burned in the engine102, and the like. In one embodiment, the detection of a non-destructivetemperature event may be a confirmation of proper operation of acomponent or process.

In one embodiment, the thermal event module 204 may be configured to seta degradation indicator 210 based on the region of interest of theaftertreatment device 106 exceeding a threshold temperature. Forexample, a first temperature responder 108 may be configured to melt ata temperature consistent with a medium degradation level, and a secondtemperature responder 108 may be configured to melt at a temperatureconsistent with a severe degradation level. The thermal event module 204may set a degradation indicator 210 indicating “medium” when the firsttemperature responder 108 melts, and a degradation indicator 210indicating “severe” when the second temperature responder 108 melts. Thedegradation indicator 210 may select a degradation indicator 210 by thetype of degradation likely—for example a degradation indicator 210consistent with catalyst degradation may be set when a thermal eventlikely to degrade a catalyst on the aftertreatment device 106 occurs.

The controller 200 may further comprise a display module 212 configuredto provide the degradation indicator 210 to a display outlet 214. Thedisplay outlet 214 may comprise a computer screen, a printed report, astored data value, and/or a data value published on a network. Forexample, the display outlet 214 may comprise a displayed field on alaptop screen that can be read by the service technician 114A.

FIG. 3 is an illustration depicting one embodiment of an apparatus 300for detecting thermal events in an aftertreatment device 106 inaccordance with the present invention. The apparatus 300 comprises atemperature responder 108 disposed within a region of interest 302 of anaftertreatment device 106, and an observation module 114 configured todetect the melting of the temperature responder 108. The region ofinterest 302 may comprise a region 302 within the aftertreatment device106 wherein thermal events may be expected to cause high stress in theaftertreatment device 106, where a regeneration temperature observationmay be considered important, and the like. For example, a thermal eventof interest within a particulate filter 106 where soot is expected tooxidize. In the example, soot may build up in the particulate filter 106toward the rear (downstream) end of the filter 106, and the region ofinterest 302 may comprise the downstream portion of the particulatefilter 106. In one embodiment, the region of interest 302 may comprisethe entire aftertreatment device 106.

In one embodiment the region of interest 302 may be radially centeredwithin the aftertreatment device 106. In an alternate embodiment theregion of interest 302, as shown in FIG. 3, the region of interest 302comprises an axial position between about 0.3 X to about 1.0 X, whereinX represents an axial position defined such that X=0 is an upstream endof the aftertreatment device, and X=1 is a downstream side of theaftertreatment device.

The apparatus 300 may further comprise a temperature responder 108disposed within an encapsulation device 304. The encapsulation device304 may be a gas impermeable chamber 304 disposed within the area ofinterest. The encapsulation device 304 may prevent the loss of thetemperature responder 108 and/or a change in properties of thetemperature responder 108 due to oxidation or other chemical effects.The encapsulation device 304 may be configured into any functionalshape. For example, the encapsulation device 304 may comprise a taperedend to facilitate ease of manufacture.

FIG. 4 is an illustration depicting one embodiment of an apparatus 400for detecting thermal events within an aftertreatment device 106 inaccordance with the present invention. The apparatus 400 comprises aplurality of temperature responders 108A, 108B, and 108C disposed withinan encapsulation device 304 disposed within a region of interest 302 ofan aftertreatment device 106. Each temperature responder 108 comprises astructure formed of a material configured to melt at a distinctthreshold temperature. The plurality of temperature responders 108 isconfigured to electrically couple the two access points 110 in aparallel electrical circuit.

The observation module 114 may be further configured to detect themelting of each temperature responder 108A, 108B, 108C based on theelectrical resistance value 112 across the two access points 110. Thethermal event module 240 may be further configured to whether the regionof interest 302 of the aftertreatment device 106 has exceeded eachdistinct temperature based on the melting of each temperature responder108A, 108B, 108C, and to set a thermal event indicator 206 based on theregion of interest 302 of the aftertreatment device 106 exceeding eachthreshold temperature. Each temperature responder 108A, 108B, 108C ofthe apparatus 400 may be further configured to provide a distinctelectrical resistance within the circuit. By calculating the totalelectrical resistance of the circuit formed by the temperatureresponders 108, the access points 110, and the observation module 114, adetermination may be made about which temperature responders 108 havemelted.

In one example, R_(t) is the total electrical resistance value of theparallel circuit between the access points 110, R_(a) is the electricalresistance of a first resistor 108A, R_(b) is the electrical resistanceof a second resistor 108B, and R_(c) is the electrical resistance of athird resistor 108C. In the example, the three temperature responders108A, 108B, 108C are configured to provide electrical resistance at 100ohms, 200 ohms, and 300 ohms, respectively. In the event that none ofthe temperature responders 108 have melted, R_(t) equals about 55 ohms.In the event that only temperature responder 108A has melted, R_(t)equals about 120 ohms. In the event that temperature responders 108A and108B have melted the total resistance, R_(t), equals about 300 ohms. Inthe event that all of the temperature responders 108A, 108B, and 108Chave melted the total resistance, R_(t) appears as an open circuit. Theother melting scenarios for the example can be calculated by one ofskill in the art based on the standard parallel resistance formula1/R_(t)=1/R_(a)+1/R_(b)+1/R_(c).

In one embodiment, the apparatus 400 may include a blank electricalresistor (not shown) configured such that the blank electrical resistorwill not melt under any expected conditions. The blank electricalresistor provides a baseline electrical resistance such that the accesspoints 110 never provide an open circuit electrical resistance, and canbe used for diagnostics of the thermal responders 108. For example, ifthe embodiment illustrated in FIG. 4, including the example electricalresistance values above, included a fourth resistor of 500 ohms inparallel with the thermal responders 108A, 108B, 108C, an open circuitelectrical resistance of 500 ohms would be the highest resistancenormally observed. In the example, an open circuit electrical resistanceacross the access points 110 may indicate a problem that is notnecessarily due to a thermal event melting the temperature responders108A, 108B, 108C.

The schematic flow chart diagram included herein is generally set forthas a logical flow chart diagram. As such, the depicted order and labeledsteps are indicative of one embodiment of the presented method. Othersteps and methods may be conceived that are equivalent in function,logic, or effect to one or more steps, or portions thereof, of theillustrated method. Additionally, the format and symbols employed areprovided to explain the logical steps of the method and are understoodnot to limit the scope of the method. Although various arrow types andline types may be employed in the flow chart diagrams, they areunderstood not to limit the scope of the corresponding method. Indeed,some arrows or other connectors may be used to indicate only the logicalflow of the method. For instance, an arrow may indicate a waiting ormonitoring period of unspecified duration between enumerated steps ofthe depicted method. Additionally, the order in which a particularmethod occurs may or may not strictly adhere to the order of thecorresponding steps show.

FIG. 5 is a schematic flow chart diagram illustrating one embodiment ofa method 500 for detecting temperature threshold events in anaftertreatment device 106 in accordance with the present invention. Themethod 500 comprises a service technician 114A and/or manufacturingprocess (not shown) inserting 802 a temperature responder 108 into aregion of interest 302 in an aftertreatment device 106. If a check 804of the system 100 indicates that the present embodiment is a removalapplication, a service technician removes 806 the temperature responder108 from the region of interest 302 of the aftertreatment device 106after a period of operation of the aftertreatment device 106. Theservice technician 114A checks 806 the temperature responder 108 formelting by visually inspecting the temperature responder 108 for meltindications.

If the check 804 of the system 100 indicates that the present embodimentis not a removal application, a manufacturing process provides 808 twoaccess points 110 electrically coupled through the temperature responder108, and the observation module 114 checks 810 the temperature responder108 for melting by measuring the resistance value 112 across the twoaccess points 110 to determine if the temperature responder 108 hasmelted.

From the foregoing discussion, it is clear that the invention provides asystem, method, and apparatus for detecting temperature threshold eventsin an aftertreatment device. The present invention may be embodied inother specific forms without departing from its spirit or essentialcharacteristics. The described embodiments are to be considered in allrespects only as illustrative and not restrictive. The scope of theinvention is, therefore, indicated by the appended claims rather than bythe foregoing description. All changes which come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

1. An apparatus for detecting temperature threshold events in anaftertreatment device, the apparatus comprising: a temperature responderdisposed within a region of interest of the aftertreatment device, thetemperature responder comprising a structure formed of a materialconfigured to melt at a threshold temperature; and an observation moduleconfigured to detect the melting of the temperature responder.
 2. Theapparatus of claim 1, further comprising two access points, wherein thetemperature responder is configured to electrically couple the twoaccess points, and wherein the observation module is configured tomeasure an electrical resistance value across the two access points andto detect the melting of the temperature responder based on theelectrical resistance value, the apparatus further comprising a thermalevent module configured to determine whether the region of interest ofthe aftertreatment device has exceeded the threshold temperature basedon the melting of the temperature responder.
 3. The apparatus of claim2, wherein detecting the melting of the temperature responder comprisesdetermining whether the electrical resistance value is a value with anopen circuit between the two access points.
 4. The apparatus of claim 2,further comprising a plurality of temperature responders, eachtemperature responder comprising a structure formed of a materialconfigured to melt at a distinct threshold temperature, wherein eachtemperature responder is configured to electrically couple the twoaccess points in parallel, wherein the observation module is furtherconfigured to detect the melting of each temperature responder based onthe electrical resistance value across the two access points, andwherein the thermal event module is further configured to determinewhether the region of interest of the aftertreatment device has exceededeach distinct threshold temperature based on the melting of eachtemperature responder.
 5. The apparatus of claim 4, wherein eachtemperature responder comprises a distinct electrical resistance value.6. The apparatus of claim 1, further comprising an encapsulation devicecomprising a gas impermeable chamber disposed within the region ofinterest, wherein the temperature responder is disposed within theencapsulation device.
 7. The apparatus of claim 1, further comprising atleast one temperature responder disposed within each of a plurality ofareas of interest within the aftertreatment device.
 8. The apparatus ofclaim 2, further comprising an electronic control module (ECM)comprising: the observation module; the thermal event module, furtherconfigured to set a thermal event indicator based on the region ofinterest of the aftertreatment device exceeding the thresholdtemperature; and a fault module configured to set a fault indicatorbased on the thermal event indicator.
 9. The apparatus of claim 8,wherein the fault indicator comprises a member selected from the groupconsisting of an illuminated dashboard lamp, a network data value, and acommunicated signal.
 10. The apparatus of claim 8, further comprising aplurality of temperature responders, each temperature respondercomprising a structure formed of a material configured to melt at adistinct threshold temperature, wherein each temperature responder isconfigured to electrically couple the two access points in parallel,wherein the observation module is further configured to detect themelting of each temperature responder based on the electrical resistancevalue across the two access points, and wherein the thermal event moduleis further configured to determine whether the region of interest of theaftertreatment device has exceeded each distinct threshold temperaturebased on the melting of each temperature responder, and to set thethermal event indicator based on the region of interest of theaftertreatment device exceeding each threshold temperature.
 11. Theapparatus of claim 1, wherein the temperature responder comprises one ofa wire and a material deposited on a surface of a channel within theaftertreatment device.
 12. The apparatus of claim 1, wherein thetemperature responder is formed from a material selected from the groupconsisting of calcium, magnesium, and aluminum.
 13. The apparatus ofclaim 1, wherein the temperature responder is formed from a materialselected from the group consisting of copper (Cu), silver (Ag), and gold(Au).
 14. The apparatus of claim 1, wherein the temperature respondercomprises a metal alloy.
 15. The apparatus of claim 14, wherein themetal alloy comprises a eutectic metal alloy.
 16. The apparatus of claim15, wherein the eutectic metal alloy comprises a Pt—Ti eutectic meltingat about 840 degrees C.
 17. The apparatus of claim 1, wherein the regionof interest comprises an axial position within the aftertreatmentdevice, the axial position between about 0.3 X to about 1.0 X, wherein Xrepresents an axial position defined such that X=0 is an upstream end ofthe aftertreatment device, and X=1 is a downstream side of theaftertreatment device.
 18. A method for detecting temperature thresholdevents in an aftertreatment device, the method comprising: inserting atemperature responder into a region of interest in the aftertreatmentdevice, the temperature responder comprising a structure formed of amaterial configured to melt at a threshold temperature; check thetemperature responder for melting after a period of operation of theaftertreatment device; and determine whether the region of interest ofthe aftertreatment device has exceeded the threshold temperature basedon the melting of the temperature responder.
 19. The method of claim 18,wherein checking the temperature responder for melting comprisesremoving the temperature responder from the region of interest in theaftertreatment device and visually inspecting the temperature responderfor melt indications.
 20. The method of claim 18, wherein checking thetemperature responder for melting comprises providing two access pointselectrically coupled through the temperature responder, and measuringthe electrical resistance value across the two access points todetermine if the temperature responder has melted.
 21. A system fordetecting temperature threshold events in an aftertreatment device, thesystem comprising: the aftertreatment device configured to treat anexhaust gas of an internal combustion engine; a temperature responderdisposed within a region of interest of the aftertreatment device, thetemperature responder comprising a structure formed of a materialconfigured to melt at a threshold temperature; two access points,wherein the temperature responder is configured to electrically couplethe two access points; an observation module configured to measure anelectrical resistance value across the two access points, and detect themelting of the temperature responder based on the electrical resistancevalue across the two access points.
 22. The system of claim 21, furthercomprising an electronic control module (ECM) comprising: theobservation module; a thermal event module configured to determinewhether the region of interest of the aftertreatment device has exceededthe threshold temperature based on the melting of the temperatureresponder, and to set a thermal event indicator based on the region ofinterest of the aftertreatment device exceeding the thresholdtemperature; and a fault module configured to set a fault indicatorbased on the thermal event indicator.
 23. The system of claim 21,further comprising a service tool comprising: the observation module; athermal event module configured to determine whether the region ofinterest of the aftertreatment device has exceeded the thresholdtemperature based on the melting of the temperature responder, and toset a degradation indicator based on the region of interest of theaftertreatment device exceeding the threshold temperature; and a displaymodule configured to provide the degradation indicator to a displayoutlet.
 24. The system of claim 23, further comprising a plurality oftemperature responders, each temperature responder comprising astructure formed of a material configured to melt at a distinctthreshold temperature, wherein each temperature responders is configuredto electrically couple the two access points in parallel, wherein theobservation module is further configured to detect the melting of eachtemperature responder based on the electrical resistance value acrossthe two access points, and wherein the thermal event module is furtherconfigured to determine whether the region of interest of theaftertreatment device has exceeded each distinct threshold temperaturebased the melting of each temperature responder, and to set thedegradation indicator based on the region of interest of theaftertreatment device exceeding each threshold temperature.
 25. Thesystem of claim 23, further comprising: a plurality of temperatureresponders, each temperature responder comprising a structure formed ofa material configured to melt at a distinct threshold temperature; twoaccess points corresponding to each of the temperature responders,wherein each temperature responder is configured to electrically couplethe two corresponding access points in parallel; wherein the observationmodule is further configured to detect the melting of each temperatureresponder based on the electrical resistance value across the twocorresponding access points; and wherein the thermal event module isfurther configured to determine whether the region of interest of theaftertreatment device has exceeded each distinct threshold temperaturebased the melting of each temperature responder, and to set thedegradation indicator based on the region of interest of theaftertreatment device exceeding each threshold temperature.